MPDN is a modern extensible media player written in .NET (with performance critical parts in ASM/SSE2) featuring a fully integrated high quality Direct3D 9, 10, 11 video renderer that is equally extensible. In fact, its most powerful features come from its open source community contributed extensions called MPDN Extensions hosted on GitHub. Both madVR and MPV use portions of code from MPDN Extensions.

Custom Linear Scalers
These custom linear scalers extend MPDN by adding Sinc-Blackman, Gaussian etc. scaling options. If there's a new scaler you want to add, give it a kernel function and MPDN will do the rest. The same custom scalers can also be used in the EWA scaler (via Render Script).

Render Scripts
Render Scripts are quite similar to AviSynth scripts and plugins except they run fully on the GPU. You can script Render Scripts in a similar fashion to AviSynth with a C# syntax, or an AviSynth-like syntax with the full power of JavaScript behind it. As opposed to madVR's mostly closed source nature, MPDN's Render Scripts are fully open source and are hosted on GitHub.

EWA (Elliptical Weighted Average) Scaler with Jinc or any CustomLinearScalers

Debanding

DXVA HD scaler

Any legacy pixel shader pre/post-scale filters such as FineSharp

and more... with presets via hotkeys

Audio Scripts
Audio Scripts are similar in concept to Render Scripts except they operate on audio samples. Audio Scripts can run purely on the CPU, interface with third party audio libraries or with OpenCL via Cudafy. See this 2x Audio Gain example.

MPDN
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v2.49.0 Changelog:
Show more informative error messages
Fix: Some usage paths may lead to old ditherers being used instead of the new ones
v2.48.0 Changelog:
Improved fluid motion by timing frames more accurately
Improved dithering methods (especially ordered dithering)
Fixed: Pixels were misaligned when there was an unequal number of blank lines on either side of the image.
v2.47.0 Changelog:
MPDN is now signed with a commercial code-signing certificate